The ozone hole, is technically not a ‘hole’, meaning that there is no ozone present. This hole is actually a region of great depletion of ozone present in the stratosphere. The ozone hole above the Antarctic over the south pole, and appears every spring since the 1980’s. There has also been a depletion of ozone in the stratosphere in both hemispheres of the Earth too (EPA, 2018). Ozone is naturally created in the stratosphere when oxygen (O2) get broken up by UV light into two free oxygen molecules, these free atoms then can bond with some unbroken oxygen creating ozone (O3). Amplify this reaction in the stratosphere, and the ozone layer is created, and blocks off most UV light from getting to Earth. These UV rays if not mostly blocked can cause skin cancer and cataracts in humans, as well as reproductive problems in fish, crabs, frogs and even phytoplankton. To make things worst ozone is unstable and is easily broken down up by trace elements (Handwerk, 2010).
Invented in the 1920’s, chlorofluorocarbons (CFCs), created an exceptionally difficult situation for the ozone layer. These CFCs would escape into the atmosphere, even though they are heavier than air, mostly via refrigerants, solvents, and aerosols. In the lower atmosphere they are so stable that they can persist for years, even decades. This long life time allows some of the CFCs to reach the stratosphere. In the stratosphere, UV light can break apart the CFCs and produce free chlorine atoms. This chlorine then can destroy ozone molecules by ‘stealing’ their oxygen atoms. One chlorine atom can destroy many ozone molecules (NASA Ozone Watch , 2018) Under normal atmospheric conditions, the two chemicals that store chlorine in the atmosphere (hydrochloric acid and chlorine nitrate) are stable. In the long months of polar darkness in winter in Antarctica the atmospheric conditions are unusual. The darkness means cold temperatures which cause clouds to form even in a place that is so dry. Reactions take place on those clouds with the chlorine cause into to become more active. When the sunlight returns, the new UV light brakes the chlorine atoms into gas and releasing them into the stratosphere, where it can destroy ozone and cause the ozone hole (NASA Ozone Watch , 2018).
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The discovery of the ozone hole created a bit of an outroar. The threat of more UV light because of ominous hole in the ozone layer, made people notice that the negative aspects to CFCs. The recognition of these harmful aspects of CFCs lead to the Montreal Protocol on Substances That Deplete the Ozone Layer in 1987. This agreement to phase out these substances was signed by all 197 United Nations member countries. This agreement made a dramatic affect upon the ozone’s future. Without the pact the U.S would have seen an additional 280 million cases of skin cancer, 1.5 million skin cancer deaths, and 45 million cataract instances, and the world would be 25% hotter today (Nunez, 2019).
More than 30 years after the Montreal Protocol, NASA scientist have documented the first direct proof that the ozone hole is truly recovering because of the CFC phase down. The ozone depletion in the Antarctic has reduced by 20% since 2005, and at the end of 2018 the assessment has predicted that the ozone depletion would be completely healed in non-polar Northern Hemisphere by 2030, in non-polar Southern Hemisphere in the 2050s, and in the polar regions by 2060 (Nunez, 2019). These predictions can be seen in figure 1. These results show that the global response to the depletion of the ozone layer has made a dramatic difference today, and even more into the future. The movement made against the imminent threat of the ozone hole, is one of the only environmental success stories, showing that when people band together for the environment, and action occurs people can help save our world.
Oil spills or leaks happen when oil is spilled into a body of water. They occur anthropogenically, when problems occur in oil tankers, storage facilities, underwater pipelines or offshore oil-drilling rigs, or naturally via oil seeps which a leaks from fractures or sediment. When these spills or leaks occur, they lead to quantities of oil polluting the water (Chow, 2010). The clean up and remediation of an oil spill is a difficult job, as no two spills can be exactly alike. Variables such as the oil type, location, amount of oil spilled, weather conditions and proximity to sensitive areas are always different. For example the oil spill in figure 2 is going to be different to a spill that may occur tomorrow. These variables then affect the best ways to approach, treat and clean an oil spill (Louisiana Oil Spill: Applied Research & Development, 2010).
The pollution of the water caused by an oil spill effects the surrounding aquatic systems if left unchecked. This can lead to seabirds with oil coatings, causing the loss of insulation in their feather because the oil separates the birds feathers causing all trapped heat to escape and the waterproofing to be impaired. These birds that then have oil on them will want to preen their feathers ultimately leading to them ingesting the oil, which can poison them (International Bird Rescue, 2011). Oil can also cause adult fish to have fin corrosion (National Ocean Service , 2018). Ultimately the severity of environmental damage caused by an oil spill depends on many factors, including the location of the spill, wildlife in the area, time of year regarding breeding and migrations, and the weather at sea (West, 2019).
To leave an oil spill to disperse by itself, is to leave the entire ecosystem the oil is within to the mercy of the oil. Sometimes if the spill is extremely small and the oil is not thick and is able to disperse through the water naturally and quickly, to leave it can be considered. Sadly though most spills cannot be cleaned completely by natural dispersion. There is microbes present in the ocean that can digest and breakup an oil spill, helping with the natural dispersion but with large, thick or surface oil spills, the microbes cannot clean it up in the way other methods would (Science Learning Hub, 2012).
There is currently many methods to clean up oil spills, including burning the fresh oil, booms that contain the oil within floating barriers allowing skimmers to suck or absorb up the oil, or dispersants. Dispersants must be used within the first couple of days of the spill, but is one of the most common ways currently being used to treat oil spills (Science Learning Hub, 2012). It is not often when a large oil spill occurs but when it does, the way to clean it up includes multiple of these methods.
Dispersants helps to stop the pollution of beaches with oil and the coating of oil on surface dwelling animals. This means that some of the effects of an oil spill is limited. Dispersants can be toxic substances, although today's products are less damaging than the toxic solvents used in earlier spills. The main problem with dispersants relates to the fact that they help to spread oil widely into the environment, though that is what natural dispersion does anyway, dispersants just help to speed up the reaction (Cressey, 2010). This speeding up of the reaction, is how dispersants limit the spread of surface oil on the water and helps prevent it from reaching the land.
To clean up an oil spill completely is to eradicate the oil from the water. With todays methods of cleaning oil spills we cannot remove all the oil from a spill. All we can do is limit is impacts, and our current methods are the best we have. To leave the oil spill to naturally disperse would take a long time and just spread it more into the ocean. Also the reliance on these microbes, can be misplaced, with the microbes possibly not present in the numbers needed or not enough nutrients present to sustain the microbes (Vergeynst, 2018). The oceans ecosystems are too delicate to leave a oil spill unchecked meaning that oil spills must be cleaned up, not left for nature to do the best it can. People in this instance can intervene and do a better job than what nature can do .
Desertification is when land can no longer support the same plant growth it had in the past, and the change is permanent on a human time scale. This means that desertification refers to the permanent degradation of land. Desertification causes dramatic problems in reference to economic, social and environmental conditions in already arid areas. It can affect food security, international trade, national economic statuses, and the lives of the people living in the affected areas (Jabbar & Chen, 2012). Salination or the development of salt affected soils (saline and sodic) is a degradation process that usually leads to desertification of lands, like in Figure 3.
[image: Why Students at Environmental Science Schools Fight Desertification]There is two main types of salinity: primary and secondary. Primary salinity refers to naturally occurring salinity in soils and water, for example salt lakes and salt pans. Whereas secondary salinity results from human activities, usually land development and agriculture. Examples include irrigation, and intrusive agriculture (Queensland Government, 2017). Secondary salination is associated with the introduction of irrigation into the dry lands like Thar Desert and Sharda Sahayak in India which has caused desertification due to the rise of salts with the rise of ground water (Singh, 2008). Most of the salt affected soils are confined to arid or semi-arid areas. As these areas are already at threat of becoming desert, the salt becomes the causative factor triggering the desertification.
In general, salt affected soils create water shortfalls making the survival of natural vegetation and crops difficult, even impossible. These moisture shortfalls is due to the difficulty of plants using the water in the soil (saline soils), or to the difficulties for root development and waste infiltration into the soil (sodic soil). Saline soils are high in salts and sodic soils are high in sodium. Sodic soils have a high sodium content but sometimes not linked to salinity. Though salt can contain sodium causing it to create both a saline and sodic soil. Both of these types of spoils are linked to the salination and desertification of land (Rubio, et al., 2005). Also if the level of salts is too high in the soils water, water may flow from the plants roots back into the soil, instead of being absorbed into the plant. This can result in dehydration of the plant and causes the yield of the plant to decline, ultimately to the plants death (Queensland Government , 2016).
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